An aqueous coating composition is described in U.S. Pat. No. 4,092,279 to Piskoti in which a composition containing water, a latex binder, an emulsifying agent, a filler, a thickening agent, and a compound which imparts shear stability to the composition is applied to the side-wall area of a green tire carcass, and the carcass is then molded to the desired configuration.
One of the disadvantages of the composition described in U.S. Pat. No. 4,092,279 is that the identifying markings on the rubber article are obscured. Other problems which have plagued the tire manufacture is entrapped air which causes blemishes on the sidewalls and thereby results in a high rejection rate during manufacturing. Moreover, some of the compositions which have been employed heretofore have left a residue on the mold surface, which builds up over a period of time and results in defects on the sidewalls of the tire. Also, some of the compositions employed heretofore do not provide adequate air bleed characteristics, do not have sufficient lubricating properties and will flex crack upon molding. Furthermore, some of the compositions are not stable on storage and cannot be sprayed after standing for a period of time.
Therefore, it is an object of this invention to provide a composition which may be applied to rubber articles to improve their molding characteristics. Another object of this invention is to provide a composition which aids in the molding of green tire carcasses to eliminate blemishes such as folds, "lights" (unfilled voids), knit failures and cracks on the sidewall surface of the tire. Another object of this invention is to provide a composition which is compatible with and will adhere to the tire carcass. Still another object of this invention is to provide a composition which will not flake or flex crack on the tire carcass. Still another object of this invention is to provide a composition which is stable during storage and is easily applied to the rubber surface. A further object of this invention is to provide a composition which will aid in the removal of entrapped air during molding of green tire carcasses A further object of this invention is to provide a composition which will not impair the weatherability and aging characteristics of molded rubber articles A still further object of this invention is to provide a mold release composition which will not build up on the mold surface. A still further object of this invention is to provide a transparent coating on the tire surfaces which will permit identifying markings to remain readable during and after the molding process.